Chopstick technique used in laparoendoscopic single site radical hysterectomy for early stage cervical cancer

Laparoendoscopic single-site surgery (LESS) further minimizes the invasiveness of traditional laparoscopic surgery. However, the "chopstick" effect caused by the parallel arrangement of the instruments in the umbilicus is considered an obstacle indelicate operations. The purpose of this study was to introduce a new technique characterized by a double fulcrum formed by instruments, named the "chopstick" technique, which facilitates the expedient accomplishment of complicated surgeries such as LESS radical hysterectomy (LESS-RH). Seventy-three patients who underwent LESS-RH using the "chopstick" technique were retrospectively analyzed. The procedure was performed successfully in 72 patients. The median operative duration was 225 min, and the median intraoperative blood loss was 200 ml. Among the operations in the first 20 patients, intraoperative vascular injuries and bladder injury occurred in two patients and were repaired by LESS. Patients responded positively regarding minimal postoperative pain control. The score of satisfaction with the cosmetic outcome expressed by the patients was eight at discharge and nine 30 days later. In conclusion, this study presents the feasibility of accomplishing complicated procedures, such as radical hysterectomy, by LESS using the “chopstick” technique. This approach provides more options for both selected patients and surgeons.

Arrangement of the instruments for a double fulcrum. Two instruments were inserted into the abdominal cavity through two independent channels placed symmetrically to the left and right of the navel, and a 10-mm laparoscope was inserted at the upper part of the incision between these two channels. The two separate channels of the medium-soft port provided a double fulcrum for the forceps, and the chief surgeon stood on the cephalic side of the patient such that his arm was parallel to the forceps (Fig. 2).
Operative procedure for ureteral unroofing. Separation of the ureter from the cervix and vagina is a critical step of RH, which requires many delicate maneuvers. The vesicocervical space and the anterior leaf of the vesicocervical ligament were exposed by a grasper in the surgeon's left hand. Serial dissection of the vesicocervical ligament was extended to the level of ureteral insertion into the bladder by a Harmonic Scalpel in the right hand. The anterior leaf of the vesicocervical ligament is short, so the tips of the two instruments were very close to each other. The grasper in the left hand was fixed to maintain a certain tension; meanwhile, the Harmonic Scalpelin the right hand was able to move around its own fulcrum without disturbing the stability of the grasper. Thus, the roof of the ureter tunnel was opened.
Postoperative treatment and follow-up. After surgery, patients with two or more intermediate-risk factors 8 (LVSI, tumors > 4 cm, and deep cervical stromal invasion) were recommended to receive adjuvant radiation therapy, whereas patients with one or more high-risk factors 9 (resection margin involvement, parametrial involvement, or lymph node involvement) were recommended to receive adjuvant concurrent chemoradiation therapy. However, some patients received adjuvant chemotherapy based on the preferences of the patient and  Outcomes. Clinical data, including patient demographics and perioperative measures, were obtained from a retrospective chart review following approval by our institutional review board. The operative duration was recorded from the first skin incision to the last suture (skin to skin). Blood loss was estimated from the contents  www.nature.com/scientificreports/ of suction devices. The length of hospital stay was counted from the 1st postoperative day. Intraoperative complications included procedure-related organ damage and events for which intravenous medications (including blood transfusions) were needed. Postoperative complications were defined as complications occurring postoperatively up to 8 weeks after surgery 10 . Postoperative complications were graded using the Clavien-Dindo (C-D) classification of surgical complications. The cosmetic outcome of the umbilical scar was evaluated by patients on days 1 and 30 after surgery. A subjective satisfaction score ranging from 1 to 10 (with 0 being "bad" and 10 being "excellent") was assigned 11 .
Statistical methods. SPSS 17.0 (IBM Corp, Armonk, NY, USA) was used for statistical analysis. All data were analyzed and reported as numbers (%) or medians (ranges).

Results
A total of 73 patients were included in the study. Of these, 72 patients (98%) underwent LESS successfully, and one patient was converted to multiport laparoscopic surgery due to stage 4 endometriosis. The 72 patients' characteristics are presented in www.nature.com/scientificreports/ and para-aortic lymphadenectomy was performed in 26(36.1%) patients. The median operative duration was 217 min, and the median intraoperative estimated blood loss (EBL) was 200(10-800) ml. Postoperative pain was evaluated at 24 h and 48 h after surgery, at which time the median visual analog pain scale score at rest was 3(0-6) and 2(0-4), respectively. The time it took to achieve a postvoid residual urine volume of less than 100 ml after removal of the urethral catheter was 14(3-100)days. The median length of postoperative hospital stay was 8(2-18) days.The median cosmetic outcome satisfaction score expressed by the patient was 8(7-10) at discharge and 9 (range, 8-10) 30 days later. Two intraoperative complications were observed in the first 20 patients, including 1 patient with bladder injury and concurrent left external iliac vein injury and one patient with left external iliac vein injury; these injuries were repaired by LESS with no long-term sequelae. Postoperative complications were documented in 15 of 72 (20.83%) subjects (Table 3). Thirteen patients (18.1%) had minor complications classified as C-D grade II or less, while three patients (4.2%) had complications categorized as C-D grade III. One case of ureterovaginal fistula was first diagnosed at 14 days postoperatively and was treated immediately with ureteroneocystostomy. One patient was diagnosed with paralytic ileus, and a nasogastric tube was placed to relieve abdominal distention. One case of lymphoid leakage occurred, for which a drainage tube was placed through the vagina, and the condition improved seven days later.
The median number of pelvic and para-aortic lymph nodes resected was 18 (10-31) and 6(4-18), respectively. Positive pelvic nodes were identified in 13 patients (18.1%). Pathological examination of the vaginal margin status yielded negative findings. Positive parametrium was found in 1 patient, deep stromal invasion in 37 patients, and LVSI in 13 patients. Twenty-eight patients were treated with postoperative concurrent chemoradiotherapy, 11 patients with intermediate-risk factors were treated with radiotherapy, and three patients were treated with chemotherapy postoperatively (Table 4).
After a median follow-up duration of 29 months(16-39), five patients had recurrence. The anatomical site of recurrence was the vaginal stump in one patient, the pelvis in one patient, the pelvic and para-aortic lymph nodes in one patient, and the lung in 2 patients.
There was one case of mortality. The patient had FIGO stage IIa1 squamous cell carcinoma with no intermediate-risk factors or high-risk factors.Therefore, adjuvant therapy was not administered to this patient; however, pelvic recurrence was found six months after surgery. She received adjuvant chemoradiotherapy and died 15 months after recurrence.

Discussion
This report demonstrates the feasibility of the "chopstick" technique in operations as complicated as LESS-RH/ PLND and representsthe largest public experience in the treatment of early cervical cancer by LESS. In the majority (98%) of these 72 patients, we were able to complete the surgery without the need for conversion to multiport laparoscopy, which is comparable to recently published data for the conversion of multiport laparoscopy to laparotomy 12 . The median number of pelvic and para-aortic lymph nodes resected and the pathological results of the parametrium and the vaginal margin were the same as those of routine clinical practice.
The completion of radical hysterectomy by LESS at our institution depends on the emergence of the "chopstick" technique and its continuous development. The arrangement of forceps in LESS has been compared to that of chopsticks in many studies in the literature. Moreover, the arrangement caused the lack of a surgical triangle and increased the difficulty of the operation, which was referred to as the chopstick effect by some surgeons 7,13 . The technique introduced in our study is based on this kind of chopstick-like arrangement. More importantly, the movement of forceps during the operation is based on the same physical principle as the use of chopsticks. The use of chopsticks varies from person to person but can be divided into two categories according to physical principles: the "parallel method" and the "cross method". It is generally believed that the parallel method is correct. The key of this method is that the hand-held points of the two chopsticks are separated from each other; regardless of which fingers are used to control the chopsticks, the two chopsticks have their own independent fulcrum and do not interfere with each other ( Figure 3A). Similarly, there are two kinds of techniques for using Table 3. Hospital-and patient-reported postoperative complications (no. of surgery = 72). SPSS 17.0 (IBM Corp, Armonk, NY, USA) was used for statistical analysis.The website of SPSS is https:// www. ibm. com/ cn-zh/ analy tics/ spss-stati stics-softw are. a One patient had two complications simultaneously.   www.nature.com/scientificreports/ forceps in single-port laparoscopy, including the cross technique 14 and the "chopstick" technique we introduced. There are different principles for movement of the forceps in the two techniques. In the cross technique, the forceps are moved using a single fulcrum, while in the "chopstick" technique, the forceps are moved using a double fulcrum, similar to chopsticks when correctly used. Two considerations for obtaining the correct "chopstick technique" were necessary, including establishing a channel with a double fulcrum and changing the position of the surgeon. In single-incision three-channel laparoscopy, the double fulcrum is created by two incisions in the rectus sheath. When using the HangT port, the fulcrum is the port's channel, whose distance is fixed as designed by the manufacturer (Fig. 3B). To allow the surgeon's arm and the instrument to become parallel and form the chopsticks that move around the fulcrum to perform pelvic surgery, the surgeon needs to stand on the patient's cephalic side.

Clavien-Dindo grade I-II (mild)
On account of the challenges of LESS, there has been extensive development of instruments and surgical techniques. Many specialized instruments, including a flexible-tip laparoscope and some articulating or prebent instruments, have been invented to provide more space for a surgical triangle. However, their actual efficacy needs further verification. Robotic systems, such as the da Vinci Si Surgical System, also require space in the surgical field to provide manipulators with high degrees of freedom 13 . However, the efficiency of both EndoWrist movements and semirigid manipulators has been criticized, and the drawbacks of this new technology in LESS have been noted. Several surgical techniques have been described in the literature to solve the mutual influence of two hands due to adjacent instruments. In the glove-port technique 15 and the cross-handed technique 14 , the instruments are arranged specifically, shown as the right instrument on the left side of the target and the left instrument on the right, which is known as the "cross" technique (Fig. 3C). The two instruments enter the abdominal cavity through the umbilical single-port access device, forming a cross in the abdominal wall, which is the instrument's fulcrum. Although these techniques can be used to perform most basic gynecological operations, the instruments may interfere with each other because of their joint fulcrum. It is generally agreed in LESS that the farther apart the two instrument tips are, the more convenient the operation is to avoid collisions between the two hands. However, when a delicate maneuver is performed in laparoscopic surgery for gynecological cancers, especially in dissection of the vesicocervical ligament, the tips of the instruments need to be very close. Thus, the "chopstick"technique may havea more significant advantage inthis context because of its two independent fulcrums.
The proportion of women successfully treated by the intended approach without conversion to another approach is often used as a primary outcome to evaluate a new operation. Regarding our results, the conversion rate was 2%, which is lower than that reported by Boruta in their early experience with LESS-RH, wherein the procedure was converted to laparotomy in 2 of 22 women 16 . With any new surgical technique, an assessment of the operative duration and EBL is essential in determining feasibility and safety. The operative duration (251 min) and EBL (200 ml) were not significantly affected by the proposed technique. Moreover, complications did not increase, with a rate of C-D grade III-IV complications of 4.2%. The three cases of severe intraoperative complications consisting of bladder injury and external iliac injury occurred in the first 20 patients treated by different surgeons, which indicates that individual surgeons need to go through alearning curve to master the new technique. All patients were delighted with the cosmetic results and postoperative pain control, which may be advantages of LESS. No cancer cells were observed at the outer edge of the tissue that was removed in our LESS series. The median number of lymph nodes retrieved was similar to that reported for multiport laparoscopy or laparotomy, further supporting the feasibility of LESS 11,17,18 .
We cannot deny that the recurrence rate in this study is higher than that in the laparoscopic approach to cervical cancer (LACC) study, but there is not much difference compared with the rates in previous retrospective studies. There are many influential factors of the oncological outcome, and the effect of the surgical approach and technique needs further research. After the LACC trial was published in the New England Journal of Medicine, the minimally invasive treatment of cervical cancer became controversial. Patients were to be carefully counseled if minimally invasive surgery was offered. However, a complete abandonment of minimally invasive surgery would seem excessive. The purpose of our study is only to show that the "chopstick" technique is feasible to perform and is one of the available minimally invasive treatment options in surgery for gynecological tumors.
Limitations. Although 72 RH procedures were successfully performed with this technique, there are still limitations. First, the surgeon is far away from the operative field, which leads to a great deal of strain on the surgeon's back. In addition, the chief surgeon's position may occupy the anesthesiologist's territory and carry the risk of compressing the tracheal tube. At present, this technique has only been applied at our institution. There are only observational data, and no comparative studies with other techniques have been performed; hence, the feasibility and safety of the technique have not been fully affirmed.

Conclusion
In this study, we used the "chopstick" technique to complete LESS-RH/PLND in 72 patients with early cervical cancer, confirming the feasibility of the "chopstick" technique in complex surgery for gynecological tumors. The advantages of the "chopstick" technique are the double fulcrum, usage of traditional instruments, and bimanual operation. However, this was a single-center study of LESS. More extensive clinical research is needed to confirm the universal value of the "chopstick" technique.